Add tutorial to bridge SBY token with LayerZero (#539)

* Aded Layer Zero doc

* Update AstarEVM-zkEVM.md

typo

* Update AstarEVM-zkEVM.md

* Update AstarEVM-zkEVM.md

---------

Co-authored-by: Ivan <[email protected]>
Co-authored-by: Megan Skye Phoenix <[email protected]>

docs/build/zkEVM/integrations/bridges-relays/AstarEVM-zkEVM.md

@@ -0,0 +1,50 @@
+---
+title: Astar EVM <-> zkEVM Bridge
+---
+
+## Overview
+
+:::note
+Please note that the LayerZero bridge is only available between Shibuya and zKatana testnets at this time. In this walkthrough we will describe how to bridge Shibuya token to zKatana.
+:::
+
+A LayerZero integration functionally connects the EVM on Astar parachain to the zkEVM on Ethereum. This takes the form of two smart contract-based endpoints that allow the chains to send messages to one another other. 
+
+## LSBY Token
+
+LayerZero has a standard for synthetic assets that can be locked on a source chain and minted on another called Omnichain Fungible Token or **OFT**, which we will refer to going forward. 
+
+For this walkthrough, on the Shibuya side, the contract is [NativeOFT](https://github.com/LayerZero-Labs/solidity-examples/blob/main/contracts/token/oft/v2/fee/NativeOFTWithFee.sol), which acts as an ERC20 wrapper contract (the function is payable) so you can send it some SBY tokens, and it will respond by sending a cross-chain message to the OFT contract on zKatana to mint LSBY, otherwise known as LayerZero (synthetic) SBY.
+
+On the zKatana side, the contract is [OFT](https://github.com/LayerZero-Labs/solidity-examples/blob/main/contracts/token/oft/v2/fee/OFTWithFee.sol), which acts as the ERC20 SBY synthetic asset on zKatana, which should exist in a 1:1 ratio with its NativeOFT counterpart. 
+
+### Bridging LSBY Tokens
+
+To facilitate token transfer, we have provided a sample repository containing a utility script:
+
+:::info
+
+Note: The current method is provisional and specific to testnet environments. The eventual mainnet implementation will incorporate the bridging of Native ASTR tokens through the Astar Portal.
+
+:::
+
+1. Fork the [Repository](https://github.com/AstarNetwork/layer-zero-bridge-contracts-testnet)
+
+2. Install dependencies by running `npm install`
+
+3. Create a .env file (based on the .env.example) in the root directory 
+
+4. Add your [private key](https://support.metamask.io/hc/en-us/articles/360015289632-How-to-export-an-account-s-private-key) in the .env file
+
+5. Run `npm hardhat compile` to compile the contracts
+
+#### Shibuya EVM &rarr; zKatana
+To send 1 SBY from shibuya-testnet to zkatana-testnet, run the following command (Note that the --quantity flag is in wei):
+
+`npx hardhat astarWithFeeSend --quantity 1000000000000000000 --target-network zkatana-testnet --network astar-testnet`
+
+#### zKatana &rarr; Shibuya EVM
+
+To send 1SBY from zkatana-testnet to shibuya-testnet, run the following command (Note that the --quantity flag is in wei):
+
+`npx hardhat astarWithFeeSend --quantity 1000000000000000000 --target-network astar-testnet --network zkatana-testnet`

docs/build/zkEVM/integrations/bridges-relays/astar-bridge.md

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 ---
-title: Astar Bridge
+title: ETH <-> zkEVM Bridge
 ---
 
 import bridge1 from '/docs/build/zkEVM/img/astar-bridge-zKatana-Shibuya1.jpg'